Handwriting recognition systems allow users to input handwritten data into a computer. The user writes data on an electronic tablet with a special pen, and as the user moves the pen across the tablet, the tablet displays lines to the user corresponding to the pattern travelled by the pen. These lines appear as they are written until the pen is lifted from the tablet. After a predetermined time period, or upon some user action (e.g., lifting the pen, tapping in another window), the handwritten lines are recognized as letters, symbols, numbers, or graphical shapes and translated into type.
Handwriting recognition systems use algorithms to map handwritten data to recognizable symbols. Typically, these systems store a prototype for each symbol the system can recognize. A prototype is a "picture" of a handwritten symbol that is used to map handwriting to that symbol. Recognition systems use recognition algorithms to map pen-based handwritten data to a prototype.
Prior art systems allow users to communicate with the system by drawing gestures. Gestures are special handwritten symbols that issue a command to the system. In most prior art systems, users can draw gestures whenever the pen is in what is known as write mode, as opposed to draw mode. When in write mode, a gesture must be the first symbol that a user draws. If the user draws a gesture in the middle of drawing an object, the gesture is treated as part of the object. The table below contains examples of standard, predefined gestures supported by most prior art pen-based systems. Note that some of the predefined gestures are positional, i.e., it matters where the user draws the gesture. For example, the Select Object gesture selects the object the gesture is written over. Non-positional gestures operate at the insertion point and do not need any additional context. For example, the Undo gesture reverses the last action, no matter where the gesture is written.
______________________________________ Action Type ______________________________________ Selection Gestures Place the insertion point Positional or select object Extend selection Positional Deletion Gestures Cut Current selection Non-positional if selection exists Positional if no selection exists Delete current selection Positional if selection exists Non-positional if no selection exists Backspace. Delete the Positional character under gesture Editing Gestures Place the checked word Selection-based or selection in the Edit Text dialog box Cut selection Non-positional Copy selection Non-positional Paste at the top of the Optional triangle (if positional) or at the insertion point Undo the previous action Non-positional ______________________________________
In prior art pen-based systems, gestures are used only to simplify minor editing tasks. No prior art systems are known that support direct manipulation tasks through the use of gestures. That is, no prior art systems allow a user to draw a gesture to modify the attributes of a graphic object. Attributes of a graphic object include line style and fill pattern.